Over coating coal tar epoxy

Discussion in 'Materials' started by rfleet1066, Oct 24, 2012.

  1. pauloman
    Joined: Jun 2010
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    Location: New Hampshire

    pauloman Epoxy Vendor

    PAR I honestly don't know, but doubt it.... 'tar' is tar and epoxies, like other coatings, don't like an oily, tar like surface. I suspect it might stick but adhesion would probably be very bad.

    - I don't like the term laminating resin. That is a marketing term. You can laminate with almost any epoxy. I would have no issues with building a boat using our solvent free floor epoxy. Generally for laminating you want a semi thick epoxy with not too much flex (and hopefully little or no blush!)

    paul
    progressive epoxy polymers inc
     
  2. Frosty

    Frosty Previous Member

    Coal tar epoxy is a very misleading term for it . It is niether oily or tar like. Infact it dries like glass which is why it is difficult to cover after its 24 hours.
     
  3. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    There's nothing misleading about an epoxy formulated with tar, being called coal tar epoxy.
     
  4. pauloman
    Joined: Jun 2010
    Posts: 268
    Likes: 10, Points: 18, Legacy Rep: 151
    Location: New Hampshire

    pauloman Epoxy Vendor

    coal tar epoxy literally has coal tar in it. The coal tar adds flex, increased water resistance and lowers the price (in theory). It also makes the epoxy roll on or brush on nicer than 'regular' epoxies. It has a tar smell until cured. The end result after application is a glossy, smooth, very pretty black epoxy. The coal tar is not obvious unless you try to paint over it (sometimes you can with fresh coal tar, depends upon the epoxy chemistry and perhaps the amount of coal tar in the formulation). The real issues come when the epoxy begins to break down with UV exposure..... However, even then, it never feels sticky and tar like (to the human touch). There are also health hazards associated with coal tar, but I suspect these hazards are worse with solvent based coal tar epoxies - the solvents transporting the coal tar into the skin...
     
  5. mastcolin
    Joined: Jun 2005
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    Location: The Netherlands

    mastcolin Senior Member

    "coal tar epoxy" can cover anything from almost all tar and little epoxy to mainly epoxy and little tar. Then you have differences in the tar...and pigmentation.

    For the user this means some of the ctes are thermoplastic almost, some bleed much worse than others, some will show bad cracking/crazing (crocodile skin look) when exposed to UV. To make generic comments with any reliability is impossible.

    Why would you want to put clear epoxy over cte? The main benefit for cte is cost, it is cheap for what you get. If you are going to extra cost of epoxy over the cte, just use real paint system eg a non cte and a proper topcoat (this may be epoxy if colour retention isn't a big issue). As mentioned you can try to seal in the cte with another primer then topcoat this (International sell this system I believe. It is 1 pack system. The weak solvents don't pull the tar out of the epoxy..but my memory of this is a little hazy)
     

  6. Frosty

    Frosty Previous Member

    It is not oily or tar like when dry. What it looks like in the tin is irrelevant isnt it?

    Coal tar derivatives have been use to cure Psoriasis as is coal tar soap.

    I have used gallons of it under the water line primed with Zinc chromate.

    I used to use red lead which is crap in comparison to zinc.
     
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